1. Field of the Invention
This invention relates to a power window apparatus used for lowering and raising a window glass of motor vehicles and a method used for controlling the power window apparatus, and more particularly to an apparatus and a method possible to detect squeezing of obstacles such as a hand and fingers very accurately and possible to convert the action of the window glass in the opening direction.
2. Description of the Related Art
Herertofore, there has been used a power window apparatus which is possible to convert the action of the window glass in the opening direction of the window by detecting squeezing of the obstacles between the window glass and a window frame during the closing movement of the window glass as shown in FIG. 7.
In FIG. 7, an armature shaft 101 of a geared motor 100 rotates according to an ON-operation of a switch 111, rotational power of the armature shaft 101 is transmitted to a worm wheel 102 and rotational power of the worm wheel 102 is transmitted to an output shaft 105 through a damper 104. The output shaft 105 is connected with a window glass 107 through a window glass-actuating mechanism 106, and rotational power of the output shaft 105 is converted into vertical movement of the window glass 107 in the opening and closing directions by the window glass-actuating mechanism 106. The armature shaft 101 is provided with a rotation detecting mechanism 108, the rotation of the armature shaft 101 is converted into a pulse signal by the rotation detecting mechanism 108 and input to a controller 109. The controller 109 is so designed as to memorize position data between the full-closed position and the full-opened position of the window glass 107 on basis of the number of rotations of the armature shaft 101.
If the rotation of the armature shaft 101 is restricted before the window glass 107 arrives at the full-closed positon, the controller 109 makes judgement that an obstacle or something is caught between the window glass 107 and a window frame by detecting that the rotational frequency of the armature shaft 101 becomes lower than a predetermined reference value through the current position data of the window glass 107 obtained by the pulse signal from the rotation detecting mechanism 108 does not indicate the arrival to the full-closed position of the window glass 107, and the controller 109 cuts the power supply to the motor 100, then supplies an electric current to the motor 100 in the reverse direction, thereby moving the window glass 107 in the opening direction of the window as much as a predetermined distance.
However, contacting area between the window glass 107 and a wether strip disposed in the window frame supporting the window glass 107 increases as the window glass 107 gets near the full-closed position, therefore frictional resistance between the window glass 107 and the wether strip is not constant during the whole length between the full-closed position and the full-opened position of the window glass 107, but becomes larger according as the window glass 107 approaches the full-closed position.
Accordingly, in the conventional power window apparatus shown in FIG. 7, there is a problem in that the window glass 107 turns back before arrival to the full-closed position and it is not possible to close the window when the reference value of the rotational frequency of the armature shaft 101 is established in a large value, and it is not possible to detect the obstacle caught between the window glass 107 and the window frame in earlier stage so that the return back of the window glass 107 may be delayed in a case of predetermining the reference value in a smaller value.